The invention relates to edible fat-containing products comprising indigestible polyol fatty acid polyesters. In particular, although not exclusively, the invention relates to such products of the emulsion type, such as margarine, dressings, ice cream, cheese and low-fat spreads. It is to be observed that the term emulsion as used throughout this application also encompasses compositions of the dispersion-type. The invention further relates to processes for the preparation of such products, in particular to processes wherein a first fat-containing fraction is mixed with a second fat-containing fraction.
Polyol fatty acid polyesters, and in particular, the sugar fatty acid polyesters, such as e.g. the sucrose fatty acid polyesters, are known as suitable low-calorie fat-replacers in edible products. Substantially indigestible for human beings they have physical and organoleptic properties very similar to triglyceride oils and fats conventionally used in edible products. Polyol fatty acid polyesters are also reported to have use as pharmaceutical agents e.g. in view of their ability to take up fat-soluble substances, such as in particular cholesterol, in the gastro-intestinal tract, and subsequently remove those substances from the human body. Accordingly, it is attractive to replace at least part of the fat in edible fat-containing products by polyol fatty acid polyesters.
It is further reported that in food products the use of polyol fatty acid polyesters which are liquid at body temperature, may give rise to the so-called problem of anal leakage. Accordingly, it is particularly attractive to replace the more solid part (hardstock) of the fat by counter-part polyol fatt acid polyesters.
Edible fat-containing products comprising indigestible polyol fatty acid polyesters are known in the art, and described in e.g. U.S. Pat. Nos. 3,600,186, 4,005,195, 4,005,196, 4,034,083, and EP Pat. Publ. Nos. 0 233 856, 0 236 288, and 0 235 836.
In this specification, unless otherwise indicated, the term `fat` refers to edible fatty substances in a general sense, including natural or synthesized fats and oils consisting essentially of triglycerides such as, for example, soybean oil, sunflower oil, palm oil, coconut oil, fish oil, lard and tallow, which may have been partially or completely hydrogenated or modified otherwise, as well as non-toxic fatty materials having properties similar to triglycerides, which materials may be indigestible, such as for example waxes, e.g. jojoba oil and hydrogenated jojoba oil, and polyol fatty acid polyesters referred to hereinafter in more detail. The terms fat and oil are used interchangeably.
In this specification the term `polyol` is intended to refer to any aliphatic or aromatic compound which comprises at least four free hydroxyl groups. Such polyols in particular include the group of sugar polyols, which comprises the sugars, i.e. the mono-, di-and polysaccharides, the corresponding sugar alcohols and the derivatives thereof having at least four free hydroxyl groups. Examples of sugar polyols include glucose, mannose, galactose, xylose, fructose, sorbose, tagatose, ribulose, xylulose, maltose, lactose, cellobiose, raffinose, sucrose, erythritol, mannitol, lactitol, sorbitol, xylitol and alpha-methylglucoside. A generally used sugar polyol is sucrose.
In this specification the term `polyol fatty acid polyester` is intended to refer to any such polyesters or mixtures thereof of which, on an average, more than 70% of the polyol hydroxyl groups have been esterified with fatty acids.
In this specification by `indigestible` is meant that at least about 70% by weight of the material concerned is not digested by the human body.
In this specification by `hardstock` is meant that part of the fat composition characterized by a slip melting point of above 36.degree. C. `Slip melting point` is defined as the temperature at which the amount of solid phase in the melting fat has become so low that an air bubble is forced upwards in an open capillary filled with the fat.
Fat-containing products and in particular, emulsion-type products such as margarines and low-fat spreads, have to comply with requirements such as oral response, thermal stability, cycle stability, spreadability, melting behaviour and the like. Often they have to comply with such requirements simultaneously.
In particular, for margarines and low-fat spreads which contain relatively large amounts of polyunsaturated components, or require increased softness at lower (refrigerator) temperatures, it can be difficult to simultaneously comply with the requirements for cycle stability, thermal stability and acceptable taste properties.
Stability against temperature changes (cycle stability) is important in view of temperature changes during transport and storage as well as temperature changes which may frequently occur during household use. Improved storage temperature cycle stability is therefore advantageous, if not essential.
Heat stability, i.e. stability in terms of the absence of phase separation and of oil exudation, determines the ambient temperatures at which the product can be used. It will be clear that heat stability requirements are dependent on the climatic zone involved.
In general the heat stability is governed by the amount of hardstock, i.e. the amount of higher melting fats. A better heat stability, however, in general will result in a deterioration of the oral response, especially after temperature cycling. This is because the oral response largely depends on the melting behaviour of the fat phase.
Although not wishing to be bound by theory, it is believed that the difficult compatibility of heat stability, good oral response and cycling stability stems from the fact that good heat stability (e.g. heat stability at 30.degree. C for 24 hours) generally requires fat blend compositions containing relatively high amounts of higher melting fat fractions such as in particular fat fractions having melting points above mouth temperature. These higher melting fat fractions are believed to be responsible for the adverse effects on oral response and cycling stability.
Generally, in conventional fat-containing products the higher melting fat fractions crystallize in mixed crystals of non-equilibrium composition, which incorporate considerable amounts of the lower-melting fat fractions. In a well formulated blend the melting point of the mixed crystals is just below mouth temperature. Accordingly, in the mouth such blends will melt entirely, not giving rise to waxiness and, in the case of emulsions, fully releasing the salt and flavour compounds present in the water phase.
However, when conventional fat-containing products are subjected to temperature cycling, the mixed crystals demix, and a separate, purer fraction of the higher melting fats crystallizes. In this process a network of crystals is formed, which, if a dispersed water-phase is present, surrounds and stabilizes the dispersed water droplets in the form of shells. In the mouth the non- or only partially melting network of crystals introduces a waxy taste, and prevents release of salt or flavour compounds from the dispersed water droplets which remain stabilized.
Conventional products displaying good heat stability often combine this property with a rather bad cycling stability and oral response. Vice versa, conventional products having improved cycle stability, due to the presence of a relatively small amount of high melting fats often suffer from a poor heat stability.
It is now one object of the present invention to provide edible fat-containing products comprising indigestible polyol fatty acid polyesters as hardstock which products are characterized by an improved combination of properties, in particular with regard to thermal stability, oral response and storage temperature cycle stability.
It has been found that, if at least a significant part of the hardstock polyol fatty acid polyesters are processed such that crystallization takes place before full mixing with the remaining fat fraction, fat-containing products can be obtained meeting the above object. These products are characterised by multi-peaked differential scanning calorimetry (DSC) curves showing separate fat peaks at both sides of 36.degree. C.
Accordingly, in a first aspect of the present invention there are provided fat-containing products comprising at least 5%, calculated by weight of the total amount of fat, of hardstock indigestible polyol fatty acid polyesters, the product having a differential scanning calorimetry curve showing at least one fat peak above 36.degree. C., and at least one fat peak below 36.degree. C.
In a further aspect of the invention there is provided a process for the preparation of fat-containing products comprising at least 5%, calculated by weight of the total amount of fat, of hardstock indigestible polyol fatty acid polyesters, the process comprising the step of initially processing the product in two or more separate fat-containing fractions under such conditions that the fat in at least one of the fractions has partly or fully crystallized before the two or more fractions have been fully mixed.
It has been found, that the fat-containing products, in particular the water-in-oil, oil-in-water and oil-in-water-in-oil emulsion types, prepared or preparable by the separate processing of fat fractions in accordance with the present invention, have greatly improved characteristics in terms of oral response, thermal stability and cycle stability.
It has further been found that the products in accordance with the invention can be formulated to have a reduced hardness at 5.degree. C. and an equal or higher hardness at 20.degree. C. compared to conventional fat-containing products based on the same components. This `flatter` hardness-versus-temperature line is especially important for household spreads, where the cold spread, straight from the refrigerator, has to be spreadable, but on the other hand should not be too soft at room temperature.
It will be apparent that an essential ingredient in the products according to these aspects of the present invention are hardstock indigestible polyol fatty acid polyesters. The hardstock polyol fatty acid polyesters may be the only such polyesters present but they may also be part of a mixture of polyol fatty acid polyesters or a polyester blend, provided the overall polyol fatty acid polyester composition comprises a sufficient amount of hardstock polyol fatty acid polyesters.
In addition to the hardstock polyol fatty acid polyesters it is possible to further include conventional hardstocks triglyceride fats. However, it is preferred that the hardstock used in the products of the invention comprises over 50%, preferably of over 80% or even 90% by weight of polyol fatty acid polyesters. Most preferably the hardstock substantially completely comprise of polyol fatty acid polyesters.
The total amount of hardstock in the products of the invention is at least 5% calculated by weight of the total amount of fat. Preferably the amount of hardstock lies in the range of 20 to 70%, the range of 30 to 50% being preferred most.
By variation of the particular blend of fatty acid residues used in the synthesis the melting point of the polyol fatty acid polyesters can be influenced. More saturated and/or long-chain fatty acid residues result in a higher melting point than unsaturated and/or short-chain fatty acid residues. The slip melting point of the hardstock polyol fatty acid polyesters preferably lies within the range of from 37.degree. to 55.degree. C., in particular of from 40.degree. to 50.degree. C.
Suitable polyol fatty acid polyesters have been defined in chemical terms hereinbefore. Preferably, polyol fatty acid polyesters derived from sugars or sugar alcohols are applied, and in particular, sugar fatty acid polyesters derived from disaccharides, such as sucrose Very suitable have been found sugar fatty acid polyesters of which at least 50% of the fatty acid residues are derived from saturated fatty acids, in particular saturated C.sub.8 -C.sub.22 fatty acid. Sucrose polyesters of which at least 70% of the fatty acid residues are derived from C.sub.12 -C.sub.18 fatty acids, are preferred.
In general fatty acids per se or naturally occurring fats and oils may be used as source for the fatty acid residues in the polyol fatty acid polyesters. Conventional techniques may be used to introduce, if necessary, the required degree of saturation. Suitable such techniques include full or partial hydrogenation, interesterification, transesterification and fractionation, and may be used before or after conversion of the polyols to polyol fatty acid polyesters.
Suitably polyol fatty acid polyesters are used which are completely or partly derived from trans-hydrogenated triglycerides or the corresponding lower alkylesters thereof, as described in EP 0 235 836. Alternatively, the desired level of trans fatty acid residues may also be introduced by first converting to the polyol fatty acid polyester and subsequent trans-hydrogenation.
As defined hereinbefore polyol fatty acid polyesters may be applied of which, on an average, more than 70% of the polyol hydroxyl groups have been esterified with fatty acids. Preferably polyol fatty acid polyesters are used with higher degrees of conversion, in particular polyol fatty acid polyesters of which, on an average, more than 85% or even over 95% of the polyol hydroxyl groups have been esterified with fatty acids.
The products in accordance with the invention in general have an overall fat content between 35 and 100% by weight. In a preferred aspect of the invention such products are water-in-oil or oil-in-water-in-oil emulsions containing 35-90% by weight of fat, margarine-type spreads having a fat content of 65-90% by weight being preferred most. In an alternative aspect of the invention such products are margarine-like products containing over 95%, in particular, about 98% of fat, such as are used for baking purposes.
In addition to the hardstock fat the products of the invention generally comprise conventional oils and fats which may be of both animal and vegetable origin. Suitable conventional triglyceride fats and oils include, optionally partially hydrogenated, coconut oil, palmkernel oil, palm oil, marine oils, lard, tallow fat, butter fat, soybean oil, safflower oil, cotton seed oil, rapeseed oil, poppy seed oil, corn oil, sunflower oil and mixtures thereof. Of these oils sunflower oil is preferred.
The non-hardstock part of the overall fat composition may also comprise indigestible oils, such as liquid polyol fatty acid polyesters. Suitably liquid polyol fatty acid polyesters, i.e. having slip melting points below 36.degree. C., can be used to replace fully or partially the non-hardstock part of the fat composition. Also, instead of separate hardstock and non-hardstock polyol fatty acid polyester fractions, polyol fatty acid polyesters which comprise both hardstock and non-hardstock fractions may be advantageously used.
It may also be of advantage to obtain high-melting and low-melting fat fractions by fractionating a single fat blend, such as partially hardened soybean oil or a sugar polyester blend comprising both solid and liquid fractions, and use the high-melting and low-melting fractions separately.
It has been well recognised that fat-containing products containing relatively large amounts of digestible polyunsaturated fatty acid residues are attractive for their cholesterol-lowering effect. Such products are in particular those in which the fatty acid residues in the digestible part of the fat composition comprise a maximum of 35% of saturated fatty acid residues. A useful characteristic to scale fat-containing products for their cholesterol-lowering effect is the ratio of polyunsaturated to saturated fatty acid residues (in this context only fatty acid residues in digestible fats are considered). The higher this ratio the stronger the cholesterol-lowering effect. Since linoleic acid is the most important polyunsaturated fatty acid, instead of the above ratio in practice the ratio of linoleic acid to saturated fatty acid residues (LA/SFA ratio) can be used.
Products in which in particular the conventional saturated fat fraction (i.e. the conventional hardstock) is fully or partially replaced by indigestible polyol fatty acid polyesters having characteristics similar to the conventional hardstock fat fraction, allow an appreciable and desirable increment in the LA/SFA ratio. In the products according to the invention LA/SFA ratios are achieved of over 5, such as 6 to 8. If so desired, LA/SFA ratios can be achieved of over 10.
Fat-containing products, such as margarines, having a high amount of unsaturated components are of course characterized by the presence of large amounts of liquid oil, which leads to the problem that it is difficult to have sufficient thermal stability and hardness. The present invention allows products displaying an improvement in the hardness, without the necessity of a decrease in the amount of unsaturated components, and without a deterioration of the oral response. The amount of polyunsaturated fatty acid residues, such as in particular linoleic fatty acid residues, in the present fat product is preferably between 30 and 80%, in particular at least 40%, or even 50 or 60% by weight of the total amount of digestible fatty acid residues present in the fat phase.
Since the considerations given hereinabove also apply for fat-containing products having lower fat contents, such as low-fat spreads with fat contents of between 35 and 65% by weight the invention is equally directed to those.
Although the invention is especially directed to products of the water-in-oil and oil-water-in-oil emulsion type, such as margarines and spreads, the advantages are equally achieved in products of the oil-in-water emulsion type, such as mayonnaise, or non-emulsion type, such as shortenings, which incorporate significant amounts of hardstock.
In the products according to the invention conventionally used fat- and water-soluble additives, such as emulsifiers, milk, proteins, preservatives, vitamins, in particular, vitamins A, D and E, salt and flavour compounds, may be incorporated.
One of the aspects of the products according to the present invention is the presence of a fat peak in the DSC-curve above 36.degree. C., i.e. a peak of which the top is located above 36.degree. C. Preferably at least 80% of the surface area of the peak, i.e. the surface area between the base line and the line generated by the differential scanning calorimeter, is above 36.degree. C. It is thus possible that part of the lower temperature tail of the peak is located below 36.degree. C. When determining the surface area of individual peaks, in case peaks overlap, it is assumed that the peaks are symmetrical.
In this specification by `peak in the DSC-curve` is meant an absolute or relative maximum in the DSC-curve. The term `fat peak` is intended to exclude those peaks or parts of peaks which are not attributable to the fat part of the product.
At least one further fat peak should be present below 36.degree. C. This may be a peak in the temperature range of 20.degree. and 35.degree. C., but also fat peaks at temperatures below this range correspond to DSC-curves in accordance with the present invention. Such fat peaks then correspond to lower crystallizing fat fractions. In the products according to the invention at least two separately melting fat fractions are present.
It is preferred that the DSC-curve surface area (as defined hereinbefore) below 36.degree. C. is at least equal to the surface area above 36.degree. C.
The DSC-temperature peaks of fat-containing products can be determined in the conventional way using a differential scanning calorimeter. A short survey of this method with some literature references is given in the Ullmanns Encyklopadie der technischen Chemie, 4. Auflage, Band 5, pages 793-795. In this application all DSC-curves are DSC-melting-curves.
The fat-containing products in accordance with the invention are characterised by at least 20% by weight of the crystallized fat being present in the form of fat particles having sizes between and 20 micrometers. Preferably at least 50% by weight of the crystallized fat is present in the form of fat particles having sizes of more than 1 micrometer.
Most preferred are products wherein at least 40% by weight of the crystallized fat is present in the form of fat particles having sizes ranging from 1-12 micrometers. In this context the term `size` is intended to refer to the maximum diameter of the crystallized fat particles.
In general the fat product of the invention has an overall N.sub.40 below 10, more preferably it has an N.sub.35 below 10 and an N.sub.20 below 30, preferably between 8 and 25. The N-values are measured by using the NMR method as described in Journal of American Oil Chemists' Society, 51 (1974), 316 by Van Putte et al.
The process for the preparation of the fat-containing products according to the first aspect of the present invention comprises as an essential step the initial split processing of the overall product in at least and preferably two separate fat-containing fractions which differ in the slip melting point of their fat fractions, such that at least partial crystallization takes place in, particularly, the fat fraction having the higher slip melting point before full mixing with the further fat-containing fractions has been effected.
In general a first separately processed fat-containing fraction is characterized by a fat phase having a slip melting point below 36.degree. C., preferably below 35.degree. C., or even 30.degree. C. This fat phase may be substantially liquid before full mixing with the further fat-containing fractions, but it has been found of advantage when the fat in the first fraction contains some crystallized fat at the point of mixing, such as at least 1% by weight, preferably between 2 and 20% by weight of the fraction.
The fat phase in the second separately processed fat-containing fraction in general has a slip melting point above 36.degree. C., preferably between 37.degree. and 55.degree., and most preferably between 40.degree. and 50.degree. C. The fat phase in this fraction, which comprises the hardstock fats or at least a significant part thereof, such as at least 60%, and preferably at least 80% by weight, in general will contain crystallized fat at the point of mixing, although also crystal formation may take place during the mixing with further fat-containing fractions provided mixing conditions are such that partial crystallization has taken place before full mixing. Typical amounts of crystallized fat in this second fat-containing fraction before full mixing are between 2 and 30% by weight, but preferably not more than 15% by weight of the fraction.
It is preferred that the slip melting points of the fats in two separately processed fat-containing fractions differ by at least 5.degree. C., more in particular 10.degree. C. The magnitude of this difference influences the beneficial effects that may be derived from the process according to the present invention; the beneficial effect being more pronounced when the difference is larger.
The separately processed fat-containing fractions may comprise only fat components, but they may also be in the form of water-in-oil or oil-in-water emulsions, such as creams.
In a preferred aspect of the process of the invention, which is particularly directed to the preparation of spreads, a first fat or fat blend is emulsified with an aqueous phase. The temperature of the water-in-oil emulsion so obtained, if necessary, is adjusted to a value below 15.degree. C., more in particular to below 10.degree. C. More preferably, the temperature is adjusted to a value between 5.degree. and 10.degree. C. It is important to apply the correct temperature, as the second fat-containing fraction (discussed hereunder) has to crystallize due to the `cold-content` of the emulsion, as preferably no further cooling steps are provided for. It is also important that the cold emulsion already has its final character, i.e. phase-inversion should have taken place already, and also the water droplet distribution should be near to its final status. The emulsion is preferably prepared by treatment in two A-units (scraped-surface heat exchangers) followed by a C-unit (pen stirrer), although it is possible to use other systems as well. The `cold` water-in-oil emulsion, preferably containing at least 1% by weight of crystallized fat, is thereafter mixed with a second fraction essentially consisting of a second fat or fat blend having a slip melting point above that of the first fat or fat blend which second fat or fat blend is at such a temperature that the solids content thereof is between 2 and 30% by weight.
More preferably the emulsion of the first fat-containing fraction comprises from 2 to 20% by weight of crystallized fat before mixing. The slip melting point of the first fat or fat blend is preferably below 35.degree. C. More preferably, the slip melting point of the fat in the first fraction is below 30.degree. C. and the slip melting point of the fat in the second fraction is above 40.degree. C. In this case a very pronounced effect is noted, namely that a product is obtained combining a high thermal stability and with a very good stability against temperature cycling presumably due to the presence of some kind of network of the second fat or fat blend. The presence of such a network, however, does not influence the taste of the fat spread negatively.
The emulsion of the first fat-containing fraction usually contains one or more emulsifiers that favour water-in-oil-emulsion, whereas also the fat- and water-soluble additives required for the final product are incorporated therein.
The second fat or fat blend comprises a partially molten fat, or a fat containing up to 30, preferably up to 25% by weight of solids, more preferably not more than 10% by weight solids (crystallized fat) at the temperature at which it is fed to the mixing unit for mixing with the cold emulsion, which temperature preferably is above 20.degree. C. At the moment of mixing the second fat or fat blend with the water-in-oil emulsion, the second fat or fat blend may be in an supercooled state, as a consequence of which retarded crystallization may occur.
In the above preferred aspect of the process of the invention the hardstock polyol fatty acid polyesters and, optionally, the high melting triglycerides present in the second fat fraction, are mixed with the cold water-in-oil emulsion, comprising crystallized low melting triglycerides, as a result of which separately crystallized fat crystals will be present in the final product. Although we do not wish to be bound by theory, it is believed that this separate crystallization is responsible for the beneficial effects obtained by the present process.
By separately preparing the cold water-in-oil emulsion, an emulsion is obtained, wherein the surface of the water droplets is almost completely occupied with crystals of the low-melting fat fraction. On mixing this emulsion with the second fat fraction a final product is obtained in which the surface of the water droplets is still occupied with the low melting fat fraction. These products have a supreme oral response because the flavour release of the water droplets is not hindered by the presence of a shell of high melting fat crystals surrounding the water droplets. The separately crystallized high melting fat fraction, however, are present in the form a network, stabilizing the product, and preventing oil exudation at temperatures as high as 30.degree. C.
The relative amounts of the two separate process streams can vary widely, depending on the type of fats and the amount of water present. A lower limit for the amount of water-in-oil-emulsion is 17.5% by weight, corresponding to 82.5% by weight of second fat fraction. The upper limit for the water-in-oil-emulsion is 97% by weight, corresponding to 3% by weight of second fat fraction. In general the contribution of the water-in-oil-emulsion will not exceed 90% by weight.
In a further aspect of the invention an alternative preferred process comprises the step of preparing a first fraction essentially consisting of a fat or fat blend which includes part of the hardstock fats. This first fat or fat blend is thereafter mixed with a oil-in-water emulsion, such as in particular a cream, comprising the major part of the hardstock fats, preferably more than 60% of the hardstock fats. The temperature and mixing profile may be essentially similar to the one described hereinbefore.
The conditions during the mixing of the two fractions of the spread can influence the product properties to a large degree. Short residence times and/or low shear favour the formation of a separate high melting crystal network. The shear rate should be low in order to prevent the substitution of low melting fat on the water droplet surface by high melting fat crystals, and also to avoid the breaking-up of the network of high melting fat crystals, which stabilizes the product.
Suitable mixers for this purpose are well-known. Examples thereof are static mixers and jet mixers. It is also possible to use a cavity transfer mixer, as described in WO-A 8 303 222.
After the mixing step, the product is fed to a packing line, without further working or cooling, and the spread is packed. The packed spread is then stored during which storage the final properties are obtained.
Another embodiment of the present invention is concerned with the inclusion of oil-soluble vitamin in edible fat-containing products comprising indigestible polyol fatty acid polyesters and digestible fat.
In U.S. Pat. No. 4,034,083 it is reported that the consumption of diets containing sucrose polyesters interferes with the absorption of vitamins A and E. This undesirable phenomenon, according to U.S. Pat. No. 4,034,083, may be overcome by fortifying the sucrose polyester type polyesters with fat-soluble vitamins. In the examples of U.S. Pat. No. 4,034,083 edible fat Containing products are described which are prepared by combining vitaminized polyol fatty acid polyesters with non-vitaminized digestible fat.
We have found now that the negative influence of indigestible polyol fatty acid polyester on the adsorption of an oil-soluble vitamin containing product, may be overcome in a very effective manner by concentrating such an oil-soluble vitamin in a distinct fat phase essentially consisting of digestible fat, said distinct fat phase being separated from another fat phase containing indigestible polyol fatty acid residues by a third phase which is essentially impervious to said oil-soluble vitamins.
Thus another aspect of the present invention is an edible fat-containing product comprising two distinct fat phases (A) and (B); fat phase (A) comprising indigestible polyol fatty acid polyesters and fat phase (B) essentially consisting of digestible fat, wherein fat phase (B) contains an oil-soluble vitamin at a concentration level that is at least twice as high as the concentration level of said vitamin in fat phase (A) and in which fat phase (A) and fat phase (B) are separated from each other by a third phase which is essentially impervious to the oil-soluble vitamin.
The term `distinct phase` is used throughout this application to indicate that such a phase is identifiable as such upon analysis of the product. Thus at a microscopic or larger scale a distinct fat phase must be recognizable, i.e. a particular discrete part of the product should have the same composition as said fat phase, whereas the remainder should have a substantially different composition. The presence of distinct fat phases may easily be established if said phases have a clearly different appearance as in that case the different fat phases are distinctly perceptible to the eye, be it that a microscope may be required to determine this. Preferably the products according to the invention, at a macroscopical scale, are essentially homogeneous.
In a preferred embodiment of the present invention fat phase (B) contains an oil-soluble vitamin at a concentration level that is at least 5 times, preferably at least 10 times as high as the concentration level of said vitamin in fat phase (A). It is to be understood that the present invention also encompasses products in which the fat phase (B) contains an oil-soluble vitamin and fat phase (A) contains no such oil-soluble vitamin at all. In such case fat phase (B) contains infinitely more, i.e. more than 5 times as much oil-soluble vitamin than fat phase (A). In general the present product will contain at least 0.01 ppm of an oil-soluble vitamin, calculated on the total fat content. Preferably the product will contain at least 0.1 ppm, more preferably from 1 to 1,000 ppm, most preferably from 5 to 800 ppm oil-soluble vitamin, calculated on total fat.
The benefits of the present invention are particularly appreciated in products wherein a significant part of the fat is composed of indigestible polyol fatty acid polyester. Thus, preferably, fat phase (A) constitutes at least 25 wt. % and fat phase (B) constitutes at least 5 wt. % of the total fat present in the product. More preferably fat phase (A) constitutes from 50-90 wt. % and phase (B) constitutes from 7-50 wt. % of the total fat. The edible fat-containing products according to the invention preferably contain at least 5 wt. % fat. The present invention encompasses food products like spreads, cheese, meat emulsions, mayonnaise, chocolates, dressings and ice cream. The present invention is particularly concerned with food products that in their normal use, prior to consumption, are not subjected to temperatures exceeding 37.degree. C. Examples of such products are spreads, ice cream, meat emulsions, cheese, mayonnaise and chocolates.
The third phase comprised by the present product may suitably consist of a polar liquid, preferably selected from the group consisting of water, alcohol and mixtures thereof, or alternatively of a gas, preferably air. An example of a product according to the present invention containing a third gaseous phase are chocolate strands and Parmesan cheese wherein one part of the grains contains fat phase (A) and the remainder of the particles contains fat phase (B).
In a preferred embodiment of the present invention the oil-soluble vitamin is vitamin E (tocopherol). More preferably the oil-soluble vitamin is vitamin E and the third phase consists of an aqueous phase. Since the latter vitamin is extremely insoluble in water, the vitamin will only diffuse from the digestible fat phase (B) to fat phase (A) at an extremely low rate and thus the vitamin E will remain concentrated in fat phase (B). Most preferably the oil-soluble vitamin is alpha tocopherol the intake of which vitamin is essential for human beings.
The present product may suitably comprise up till 95 wt. % water, preferably from 5-90 wt. % water. Most preferably the present product is a water-and-oil emulsion containing from 10-80 wt. % water. Here the term water-and-oil emulsion encompasses emulsions containing a continuous oil phase as well emulsions containing a continuous aqueous phase. Also bi-continuous emulsions containing both a continuous aqueous and a continuous oil phase are covered by the term water-and-oil emulsion. Preferably the present product comprises a dispersed oil phase. According to one embodiment such a product is an oil-in-water-in-oil-emulsion comprising a continuous fat phase and an aqueous phase containing a dispersed fat phase, wherein the continuous fat phase is formed by fat phase (A) and the dispersed fat phase is formed by fat phase (B) or vice versa. According to another embodiment the product comprises an oil-in-water emulsion including a continuous aqueous phase containing two dispersed fat phases of different composition, one formed by fat phase (A), the other formed by fat phase (B).
Examples of food products according to the invention of the oil-in-water-in-oil type are spreads and chocolates. Examples of food products as encompassed by the present invention of the oil-in-water type are spreads, dressings, mayonnaise, ice cream and cheese.
The digestible fat phase (B) may suitably comprise digestible fatty components such as triglycerides, diglycerides or monoglycerides. Preferably fat phase (B) is mainly composed of triglycerides, more preferably fat phase (B) essentially consists of triglycerides.
In yet another preferred embodiment of the present invention the product comprises a hardstock that contains a substantial amount of high melting indigestible polyol fatty acid polyesters. Preferably the indigestible polyol fatty acid polyesters of fat phase (A) constitute more than 50 wt. %, more preferably at least 80 wt. % of the hardstock.
The hardstock polyol fatty acid polyesters may be the only polyesters present but they may also constitute part of a mixture of polyol fatty acid polyesters or a polyester blend.
The total amount of hardstock in the products of the invention preferably is at least 5% calculated by weight of the total amount of fat. More preferably the amount of hardstock lies above 20%, the range of 30 to 60% being most preferred.
The slip melting point of the hardstock polyol fatty acid polyesters in the present product preferably lies within the range of from 37.degree. to 55.degree. C., in particular of from 37.degree. to 45.degree. C.
In addition to the hardstock fat the products of the invention generally comprise conventional oils and fats which may be of both animal and vegetable origin. Suitable conventional triglyceride fats and oils include, optionally partially hydrogenated, coconut oil, palmkernel oil, palm oil, marine oils, lard, tallow fat, butter fat, cocoa butter fat, soybean oil, safflower oil, cotton seed oil, rapeseed oil, corn oil, sunflower oil and mixtures thereof. Of these oils sunflower oil is preferred.
The non-hardstock part of the overall fat composition may also comprise indigestible oils, such as liquid polyol fatty acid polyesters. Suitably liquid polyol fatty acid polyesters, i.e. having slip melting points below 36.degree. C., can be used to partially replace the non-hardstock part of the fat composition. Also, instead of separate hardstock and non-hardstock polyol fatty acid polyester fractions, polyol fatty acid polyesters which comprise both hardstock and non-hardstock fractions may be advantageously used.
It has been well recognised that fat-containing products containing relatively large amounts of digestible polyunsaturated fatty acid residues are attractive for their cholesterol-lowering effect. Such products are in particular those in which the fatty acid residues in the digestible part of the fat composition comprise a maximum of 35% of saturated fatty acid residues. A useful characteristic to scale fat-containing products for their cholesterol-lowering effect is the ratio of polyunsaturated to saturated fatty acid residues (in this context only fatty acid residues in digestible fats are considered). The higher this ratio, the stronger the cholesterol-lowering effect. Since linoleic acid is the most important polyunsaturated fatty acid, instead of the above ratio in practice the ratio of linoleic acid to saturated fatty acid residues (LA/SFA ratio) can be used.
Products in which in particular the conventional saturated fat fraction (i.e. the conventional hardstock) is fully or partially replaced by indigestible polyol fatty acid polyesters having characteristics similar to the conventional hardstock fat fraction, allow an appreciable and desirable increment in the LA/SFA ratio. In the products according to the invention LA/SFA ratios are achieved of over 5, such as 6 to 8. If so desired, LA/SFA ratios can be achieved of over 10.
In general the fat product of the invention has an overall N.sub.40 below 10, more preferably it has an N.sub.35 below 10 and an N.sub.20 below 30, preferably between 8 and 25. The N-values are representative of the solid fat content and are measured by using the NMR method as described in Journal of American Oil Chemists' Society, 51 (1974), 316 by Van Putte et al.
Yet another aspect of the present invention is a process for the preparation of an edible fat-containing product, comprising combining a first fat containing fraction of which the fat essentially consists of digestible fat and which first fraction contains an oil-soluble vitamin, with a second fraction containing indigestible polyol fatty acid polyesters wherein the concentration level of the oil-soluble vitamin in the digestible fat of the first fraction is at least twice as high as in the polyol fatty acid polyesters of the second fraction, and subjecting the combined fractions to such mild processing conditions that the final product comprises the fat of the first and the fat of the second fraction in the form of two distinct fat phases.
The term combining as used here implies more than simply bringing together the two fractions. The combination of the two fractions should be carried out in such a manner that, at a macroscopical scale, the resulting edible fat-containing product is essentially homogeneous. On the other hand, as indicated above, the combining of the two fractions should be effected under such mild processing conditions that the two fractions remain distinguishable in the final product. Here by mild processing conditions is meant that the combined fractions are not subjected to conditions of high shear, certainly not for a substantial period of time, and furthermore that the temperature is kept relatively low. The processing temperature, after combining the two fractions, preferably is adjusted to and maintained at below 35.degree. C., more preferably below 30.degree. C.
In a preferred embodiment of the present invention the process comprises the incorporation of a fluid material that is insoluble in oil and impervious to the oil-soluble vitamin, under such mild processing conditions that the product of the process contains the fat originating from the first fraction in the form a distinct fat phase essentially completely separated from another distinct fat phase originating from the second fraction by the fluid material.
Suitably in the present process the first digestible fat containing fraction is combined with the second fraction in such a proportion that the resulting weight ratio of digestible fat to indigestible polyol fatty acid polyesters ranges from 1:20 to 1:1. Indeed the benefits of the present process are particularly appreciated if the first fraction in which the oil-soluble vitamin is concentrated is combined with a second fraction comprising the major part of the fat in the final product. Thus preferably the first fraction is combined with the second fraction in such a proportion that the resulting weight ratio of digestible fat to indigestible polyol fatty acid polyesters ranges from 1:15 to 1:3.
The first and second fat-containing fraction may consist of granular material, for instance in case each fat containing fraction is composed of cheese or chocolate grains that are mixed together, but they may also consist of a water-in-oil or oil-in-water emulsion.
In a preferred embodiment of the process according to the present invention at least one of the two fractions to be combined consists of an oil-in-water emulsion and the fractions are admixed under such conditions that the product obtained is an emulsion containing an aqueous phase comprising a dispersed fat phase. Preferably the present process comprises combining a first fraction consisting of oil or an oil-and-water emulsion with a second fraction consisting of an oil-in-water emulsion In the products so obtained, the digestible fat containing a relatively high amount of an oil-soluble vitamin is separated from the dispersed fat phase containing indigestible fatty acid by the aqueous phase, which aqueous phase acts as a barrier, preventing diffusion of the oil-soluble vitamin from the digestible fat to the indigestible polyol fatty acid polyesters.
In a preferred embodiment of the present process, the first fraction contains at least 20 wt. % digestible fat and the second fraction contains from 20-80 wt. % indigestible polyol fatty acid polyesters and from 80-20 wt. % aqueous phase.
According to a more preferred aspect of the present invention the process comprises combining a first fraction containing more than 30 wt. % digestible fat with the second fraction and cooling and working the emulsion so obtained under such conditions that an oil-in-water-in-oil emulsion is obtained. According to another more preferred aspect of the present invention the process comprises admixing a first fraction consisting of an oil-in-water emulsion to a second fraction consisting of an oil-in-water emulsion in such proportions that an oil-in-water emulsion is obtained containing from 5-90 wt. %, in particular from 20-85 wt. % fat.
The present process is advantageously employed in the preparation of edible fat-containing products of the water-and-oil emulsion type, which products are suitably prepared by subjecting to cooling and/or working. Thus, in a preferred aspect of the process according to the invention, said process includes the incorporation of from 10-85 wt. % water, cooling and/or working. The cooling and working may be effected by employing devices known in the art of spread manufacture such as: Votators.TM., crystallizers, cavity transfer mixers, cooling coils, static mixers and resting tubes provided with a wire screen.